JP7307032B2 - Electrode-defined non-suspended acoustic resonator - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to bulk acoustic resonators, and more particularly can be used to provide electrical signals to the resonator body and, optionally, to one or more conductive layers of the resonator body. Bulk acoustic resonator with one or more connection structures.

Description of the Related Art Radio frequency communications have evolved from the '1G' system of the 1980's to the '2G' system of the 1990's to the '3G' system of the early 2000's to the current '4G' system which was standardized in 2012. I've been In current RF communications, RF signals are filtered using surface acoustic wave (SAW) filters or bulk acoustic wave (BAW) filters.

Film-bulk-acoustic-resonators (FBARs) and solid-mounted-resonators (SMRs) provide current 4G RF communications with relatively Two types of BAW filters are piezoelectrically driven micro-electro-mechanical system (MEMS) elements that allow them to resonate at high frequencies with relatively low insertion loss. These BAW acoustic resonators, in one example, comprise a piezoelectric stack that includes a thin film of piezoelectric material sandwiched between a thin film top electrode and a thin film bottom electrode. The resonant frequency of such a piezoelectric stack is thickness-based or depends on the thickness of the thin films of the piezoelectric stack. The resonant frequency increases as the thin film thickness of the piezoelectric stack decreases. The thickness of the resonator is critical and must be precisely controlled for the desired resonant frequency. To achieve reasonable yields of FBAR and SMR manufacturing processes for a targeted or specified RF frequency, it is difficult to adjust different regions of the piezoelectric stack to achieve a high level of thickness uniformity. Yes, it takes time.

The 5G RF communication systems being developed will eventually replace the aforementioned lower performance previous generation communication systems operating at RF frequencies between a few hundred MHz and 1.8 GHz. 5G systems instead operate at much higher RF frequencies, eg, 3-6 GHz (below 6 GHz), possibly up to around 100 GHz.

Due to this frequency increase, the film thickness of FBAR and SMR-based RF filters for 5G applications will have to be reduced to increase the resonant frequency, which is the current state-of-the-art BAW acoustic resonator. is one of the challenges facing Reducing the piezoelectric film thickness means that the distance between the top and bottom electrodes of the piezoelectric stack is also reduced, resulting in an increase in capacitance. This increase in capacitance results in higher feedthrough of RF signals and reduces the signal-to-noise ratio, which is undesirable. The optimum piezoelectric coupling efficiency of a piezoelectric stack (including a top electrode, a bottom electrode, and a piezoelectric layer sandwiched between the top and bottom electrodes) is determined by the thickness of the piezoelectric layer, the thickness of the top electrode, and the thickness of the bottom electrode. , can result from a suitable combination with the alignment and orientation of the piezoelectric crystal. Reducing the piezoelectric film thickness to achieve the desired high RF frequency operation for 5G communications may not allow achieving optimal piezoelectric coupling efficiency, which results in higher insertion loss and higher kinetic impedance and Become. The thickness of the electrodes, either the top electrode, the bottom electrode, or both, may need to be reduced. A reduction in electrode thickness results in an increase in electrical resistivity, which leads to another undesirable constraint, namely higher insertion loss.

Furthermore, the product of frequency and quality factor (or Q) for FBAR and SMR elements is typically constant, meaning that increasing the resonant frequency results in a decreasing Q. The reduction in Q is undesirable, especially given that the highest levels of FBAR and SMR Q are approaching theoretical limits at frequencies below 2.45 GHz. Therefore, frequency doubling results in a reduction in Q factor, which is undesirable for fabricating RF devices such as RF filters, RF resonators, RF switches, RF oscillators.

A resonator body is provided that can operate generally in bulk acoustic mode, preferentially in transverse resonant mode. The bottom surface of the resonator body can be mounted or bonded to a mounting substrate or carrier while still allowing use of the resonator body as an RF filter, RF resonator, RF switch, RF oscillator, or the like.

A bulk acoustic resonator is also provided that includes a resonator body and one or more connection structures that enable electrical signals to be provided to one or more conductive layers of the resonator body. In one preferred and non-limiting embodiment or example, the one or more connection structures may be integral with and/or formed from the same layer of material as the resonator body, As a result, the bulk acoustic resonator can be a single piece. The bottom surface of the one-piece bulk acoustic resonator can be mounted or bonded to a mounting substrate or carrier while still allowing use of the resonator body as an RF filter, RF resonator, RF switch, RF oscillator, etc. be able to.

These and other features of the invention will become more apparent from the following description, which refers to the accompanying drawings.

Side view of one preferred and non-limiting embodiment or example of an unsuspended bulk acoustic resonator in accordance with the principles of the present invention (e.g., herein the first and second examples of an unsuspended bulk acoustic resonator). used to describe the 1 is a side view of one preferred and non-limiting embodiment or example of an unsuspended bulk acoustic resonator in accordance with the principles of the present invention; FIG. 1 is a side view of one preferred and non-limiting embodiment or example of an unsuspended bulk acoustic resonator in accordance with the principles of the present invention; FIG. One preferred and non-limiting embodiment in the form of interdigitated electrodes that can be used as the top conductive layer, the optional bottom conductive layer, or both of a non-suspended bulk acoustic resonator according to the principles of the present invention or 1 is an example isolated plan view; FIG. One preferred and non-limiting embodiment or example in the form of an interdigitated electrode that can be used as the top conductive layer, the optional bottom conductive layer, or both, of a non-suspended bulk acoustic resonator in accordance with the principles of the present invention. is a single plan view of the. One preferred and non-limiting embodiment or example in the form of a thin plate electrode that can be used as the top conductive layer, the optional bottom conductive layer, or both, of an unsuspended bulk acoustic resonator in accordance with the principles of the present invention. It is a single plan view. 4 is a cross-sectional view of preferred and non-limiting embodiments or examples along line AA in each of FIGS. 1-3; FIG. 4 is a cross-sectional view of preferred and non-limiting embodiments or examples along line BB in each of FIGS. 1-3; FIG. 4 is a cross-sectional view of preferred and non-limiting embodiments or examples along line AA in each of FIGS. 1-3; FIG. 4 is a cross-sectional view of preferred and non-limiting embodiments or examples along line BB in each of FIGS. 1-3; FIG. 4 is a cross-sectional view of preferred and non-limiting embodiments or examples along line AA in each of FIGS. 1-3; FIG. 4 is a cross-sectional view of preferred and non-limiting embodiments or examples along line BB in each of FIGS. 1-3; FIG. One preferred and non-limiting non-suspended bulk acoustic resonator in accordance with the principles of the present invention in which the material on both sides of the first and second connection structures and the tether conductor is removed as shown in FIGS. 7A-7B 1 is a side view of an exemplary embodiment or example; FIG. 4 is a cross-sectional view of preferred and non-limiting embodiments or examples along line AA in each of FIGS. 1-3; FIG. 4 is a cross-sectional view of preferred and non-limiting embodiments or examples along line BB in each of FIGS. 1-3; FIG. One preferred and non-limiting non-suspended bulk acoustic resonator according to the principles of the present invention in which the material on both sides of the first and second connection structures and the tether conductors has been removed as shown in FIGS. 8A-8B 1 is a side view of an exemplary embodiment or example; FIG. One preferred and non-limiting non-suspended bulk acoustic resonator according to the principles of the present invention in which the material on both sides of the first and second connection structures and the tether conductors has been removed as shown in FIGS. 8A-8B 1 is a side view of an exemplary embodiment or example; FIG. 4 is a cross-sectional view of preferred and non-limiting embodiments or examples along line AA in each of FIGS. 1-3; FIG. 4 is a cross-sectional view of preferred and non-limiting embodiments or examples along line BB in each of FIGS. 1-3; FIG. One preferred and non-limiting non-suspended bulk acoustic resonator in accordance with the principles of the present invention in which the material on both sides of the first and second connection structures and the tether conductor is removed as shown in FIGS. 9A-9B 1 is a side view of an exemplary embodiment or example; FIG. One preferred and non-limiting non-suspended bulk acoustic resonator in accordance with the principles of the present invention in which the material on both sides of the first and second connection structures and the tether conductor is removed as shown in FIGS. 9A-9B 1 is a side view of an exemplary embodiment or example; FIG. FIG. 5 is a plot of frequency versus dB for a resonator body having a bottom conductive layer in the form of thin plate electrodes and a top conductive layer in the form of interdigitated electrodes with a finger pitch of 1.8 μm. Frequency versus normalization that can be used to describe the frequency responses of the first through sixth examples of non-suspended bulk acoustic resonators described herein, particularly showing mode 3 and mode 4 resonance frequencies 4 is an exemplary plot of measured amplitudes; Side view of one preferred and non-limiting embodiment or example of an unsuspended bulk acoustic resonator in accordance with the principles of the present invention (e.g., a third example of an unsuspended bulk acoustic resonator is described herein). ). Side view of one preferred and non-limiting embodiment or example of an unsuspended bulk acoustic resonator in accordance with the principles of the present invention (e.g., the fourth and fifth examples of unsuspended bulk acoustic resonators shown herein). used to describe the Side view of one preferred and non-limiting embodiment or example of an unsuspended bulk acoustic resonator in accordance with the principles of the present invention (e.g., a sixth example of an unsuspended bulk acoustic resonator is described herein). ).

For purposes of the following detailed description, it is to be understood that the invention is capable of various alternative variations and sequence of steps, except where expressly stated to the contrary. It is also to be understood that the specific devices and methods described in the following patents are merely exemplary embodiments, examples, or aspects of the present invention. Further, in preferred and non-limiting embodiments, examples, or aspects, the quantities of elements used in the specification and claims are All numbers expressed are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following patent specification and attached claims are approximations that may vary depending on the desired properties to be obtained by the present invention. . Therefore, each numerical parameter should be interpreted at least in light of the reported number of significant digits and by applying normal rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

Also, it should be understood that any numerical range recited herein is intended to include all subranges subsumed therein. For example, a range of "1 to 10" means between (and inclusive) the minimum recited value of 1 and the maximum recited value of 10, i.e., a minimum value of 1 or greater and a maximum value of 10 or less. It is intended to include all subranges having.

It is also to be understood that the specific elements and processes illustrated in the accompanying drawings and described in the following patent specification are merely exemplary embodiments, examples, or aspects of the present invention. Accordingly, specific dimensions and other physical characteristics associated with embodiments, examples, or aspects disclosed herein are not to be considered limiting. Certain preferred and non-limiting embodiments, examples, or aspects of the invention are described with reference to the accompanying figures, in which like reference numerals correspond to like or functionally equivalent elements.

In this application, the use of the singular can include the plural and the plural includes the singular unless specifically stated otherwise. Furthermore, in this application, unless stated otherwise, the use of "or" is used even though "and/or" can clearly be used in some cases. means "and/or"; Further, in this application, unless stated otherwise, the use of "a" or "an" means "at least one."

For purposes of explanation, "end", "upper", "lower", "right", "left", "vertical ( The terms "vertical", "horizontal", "top", "bottom", "lateral", "longitudinal" and their derivatives are used to are placed in the correct position in the figure of FIG. However, it is to be understood that the examples can take on various alternative variations and sequence of steps, except where expressly stated to the contrary. It is also to be understood that the specific examples shown in the accompanying drawings and described in the following patent specification are merely illustrative examples or aspects of the invention. Therefore, the specific examples or aspects disclosed herein are not to be construed as limiting.

Referring to FIG. 1, in one preferred and non-limiting embodiment or example, an unsuspended bulk acoustic resonator (UBAR) in accordance with the principles of the present invention may be operable in a bulk acoustic mode. 2 may comprise a resonator body 4 which may comprise a stack of layers comprising, from top to bottom, a top conductive layer 6, a piezoelectric layer 8, an optional bottom conductive layer 10, and a device layer 12. can. In the example shown in FIG. 1, UBAR 2 , the bottom surface of device layer 12 can be mounted, for example, directly to a mounting substrate or carrier 14 .

2, and with continued reference to FIG. 1, in one preferred and non-limiting embodiment or example, at least the resonator body 4 of FIG. Another example UBAR 2 in accordance with the principles of the invention can be similar to the UBAR 2 shown in FIG. In an example, the bottom surface of the device layer 12 can be mounted, e.g., directly mounted to the top surface of the substrate 16, and the bottom surface of the substrate 16 can be mounted, e.g., directly mounted to the carrier 14. be able to.

3, and with continued reference to FIGS. 1 and 2, in one preferred and non-limiting embodiment or example, at least the resonator body 4 of FIG. Optional second substrate 16-1 between bottom conductive layer 10, if provided, and/or second substrate 16-1 and piezoelectric layer 8 or optional bottom conductive layer 10, if provided. Another UBAR 2 example in accordance with the principles of the present invention can be similar to the UBAR 2 shown in FIG. 2, except that it can include an optional second device layer 12-1 in between. In one preferred and non-limiting embodiment or example, when deemed appropriate and/or desirable, the resonator body 4 of FIG. not shown) and/or one or more additional substrates 16 (not specifically shown). An example of a resonator body 4 having several element layers 12 and a substrate 16 is shown in the exemplary order from the piezoelectric layer 8 or optional bottom conductive layer 10 to the carrier 14, first element Layers, first substrate, second device layer, second substrate, third device layer, third substrate, . . . and so on. In one preferred and non-limiting embodiment or example in which the resonator body 4 can include multiple device layers 12 and/or multiple substrates 16, each device layer 12 is fabricated from the same or different materials. , and each substrate 16 can be made of the same or different materials. In one preferred and non-limiting embodiment or example, the number of device layers 12 and substrates 16 can be different. In an example, the resonator body 4 includes a device layer 12-1, a substrate 16-1, a resonator and a device layer 12 as the bottommost layer of body 4 . Examples of materials that can be used to form each device layer 12 and each substrate 16 are described below.

In one preferred and non-limiting embodiment or example, one or more optional temperature compensating layers 90, 92, and 94 are deposited on the top surface of top conductive layer 6, as shown in FIGS. , if the piezoelectric layer 8 or the optional bottom conductive layer 10 is provided between it and the device layer 12, and/or if the device layer 12 (or 12-1) and the substrate 16 (or 16-1) are provided can be set between them. Each temperature compensating layer can include at least one of silicon and oxygen. In examples, each temperature compensating layer can include silicon dioxide or elemental silicon and/or elemental oxygen. One or more optional temperature compensating layers 90, 92, and 94, when provided, compensate for changes in the resonant frequency of each example resonator body 4 shown in FIGS. 1-3 due to heat generated during use. can help avoid.

In plan view, each resonator body 4 and/or UBAR 2 described herein can have a square or rectangular shape. However, resonator bodies 4 and/or UBARs 2 having other shapes are envisioned.

4A-4C, and with continued reference to all previous figures, in one preferred and non-limiting embodiment or example, one or both of conductive layer 6 and optional conductive layer 10 has rear surface 22. interdigitated electrodes 18 ( FIG. 4A ) which may include conductive lines or fingers 20 supported by a rear surface 26 and interdigitated with conductive lines or fingers 24 . In one preferred and non-limiting embodiment or example, one or both of the conductive layer 6 and the optional conductive layer 10 can include conductive lines or fingers 28 extending from the first rear surface 30. 27 (FIG. 4B). The ends of the conductive lines or fingers 28 opposite the first rear face 30 can be connected to an optional second rear face 32 (shown in phantom in FIG. 4B). In one preferred and non-limiting embodiment or example, one or both of conductive layer 6 and optional conductive layer 10 can be in the form of a conductive thin plate electrode 33 (FIG. 4C). Each line or finger 20, 24 and 28 is shown as a straight line. In examples, each line or finger 20, 24 and 28 may be a curved line or finger, a spiral or finger, or any other suitable and/or desired shape.

In one preferred and non-limiting embodiment or example, the top conductive layer 6 can be in the form of interdigitated electrodes 18 , or interdigitated electrodes 27 , or thin plate electrodes 33 . Independent of the form of the top conductive layer 6, the optional bottom conductive layer 10, if provided, can be in the form of interdigitated electrodes 18, or interdigitated electrodes 27, or thin plate electrodes 33. FIG. Below, and for purposes of illustration only, in one preferred and non-limiting embodiment or example, the top conductive layer 6 is a comb electrode 27 comprising a first rear surface 30 and an optional second rear surface 32. The optional bottom conductive layer 10 is described as being in the form of a thin plate electrode 33 . However, in combination with any one of the optional interdigitated electrodes 18, or comb electrodes 27, or thin plate electrodes 33, for the bottom conductive layer 10, the interdigitated electrodes 18, or combs, for the top conductive layer 6, This is not to be interpreted in a limiting sense, as the use of any one of electrodes 27 or thin plate electrodes 33 is envisioned.

In one preferred and non-limiting embodiment or example, if an optional bottom conductive layer 10 is provided, regardless of its shape, at least the top conductive layer 6 in the form of interdigitated electrodes 18 or interdigitated electrodes 27. can be adjusted or selected in a manner well known in the art by appropriate selection of finger pitch 38 (see, eg, FIGS. 4A-4B). , finger pitch 38=finger width+finger gap (between adjacent fingers). In instances where it is desired that each resonator body 4 instance resonate primarily, but not all, in the transverse mode relative to the thickness mode, the resonant frequency of the resonator body 4 decreases with finger pitch 38. can be increased by increasing In instances where it is desired that each resonator body 4 instance resonate primarily, but not all, in the thickness mode relative to the transverse mode, the resonant frequency of the resonator body 4 increases with finger pitch 38. can be reduced by

In one preferred and non-limiting embodiment or example, each resonator body 4 instance resonates in a thickness mode, a transverse mode, or a composite or compound mode that is a combination of thickness and transverse modes. can be done. In thickness mode resonance, the acoustic wave resonates in the direction of the thickness of the piezoelectric layer 8, and the resonant frequency varies across the thickness of the piezoelectric layer 8 and the top conductive layer 6 and optional bottom conductive layer 10. Based on the thickness of the case with it. The combination of the piezoelectric layer 8, the optional bottom conductive layer 10 if present, and the top conductive layer 6 can be referred to as a piezoelectric stack. The acoustic velocity that determines the resonant frequency of each example resonator body 4 described herein is the resultant acoustic velocity of the piezoelectric stack. In an example, the resonance frequency f can be calculated by dividing the resultant acoustic velocity _Va by twice the thickness τ of the piezoelectric stack.

In transverse mode resonance, the acoustic wave resonates in the lateral direction (x or y direction) of the piezoelectric layer 8, and the resonant frequency is determined by dividing the resultant acoustic velocity _Va of the piezoelectric stack by twice the finger pitch 38: That is, it can be obtained by f=V _a /2 (finger pitch). As the finger pitch is reduced from a large pitch size _δL to a small pitch size _δS , the frequency increase rate, PFI _Calculated , can be determined by the following equation, in an example.
PFI _Calculated = ( _δL - _δS )/ _δS
In the example, when the finger pitch 38 is reduced from 2.2 μm to 1.8 μm, the transverse mode PFI _Calculated is 22.2%. In another example, the transverse mode PFI _Calculated is 28.5% when the finger pitch 38 is reduced from 1.8 μm to 1.4 μm.

A composite mode resonance can include a thickness mode resonance portion and a transverse mode resonance portion. The transverse mode resonance L portion of the composite mode resonance is the actual or measured frequency increase PFI _Measured calculated frequency increase by varying the finger pitch 38 from a large pitch size δ _L to a small pitch size δ _S It can be defined as a ratio to PFI _Calculated . The value of transverse mode resonance L can be greater than 100% with one or more uncontrolled or unpredictable variations. In examples, the resonator body 4 can resonate in thickness mode, transverse mode, or composite mode. In the example of synthetic mode resonance, the portion of transverse mode resonance L can be 20% or more. In another example of a synthetic mode resonance, the portion of transverse mode resonance L can be 30% or more. In another example of synthetic mode resonance, the portion of transverse mode resonance L can be 40% or more.

In one preferred and non-limiting embodiment or example, the optional bottom conductive layer 10 in the form of thin plate electrodes 33 and the top conductive layer 6 in the form of comb electrodes 27 with a finger pitch 38 of 2.2 μm. can resonate in a composite mode with mode resonance frequencies of Mode 1 resonance frequency = 1.34 GHz, Mode 2 resonance frequency = 2.03 GHz, and Mode 4 resonance frequency = 2.82 GHz. can.

In the example, in a resonator body 4 having an optional bottom conductive layer 10 in the form of thin plate electrodes 33 and a top conductive layer 6 in the form of comb electrodes 27 with a finger pitch 38 of 1.8 μm, the resonator The body 4 can resonate in a composite mode with modal resonant frequencies of Mode 1 resonant frequency = 1.49 GHz, Mode 2 resonant frequency = 2.38 GHz, and Mode 4 resonant frequency = 3.05 GHz. In this example, the ratio of transverse mode resonance L out of the composite mode resonance can be L-mode 1 = 53%, L-mode 2 = 78%, and L-mode 4 = 27%, respectively. See also FIG. 10, which is a plot of frequency versus dB for the resonator body 4 of this example. In FIG. 10, each peak 82, 84 and 88 represents the response of the resonator body 4 at mode 1 resonance frequency=1.49 GHz, mode 2 resonance frequency=2.38 GHz, and mode 4 resonance frequency=3.05 GHz, respectively. represents

In an example, the mode 1 resonant frequency may also or alternatively be known as or related to a surface acoustic wave (SAW), and the mode 2 resonant frequency may also or alternatively be: Known as or related to the S ₀ (or extension) mode, the mode 4 resonance frequency is also or alternatively known as or related to the A ₁ (or bending) mode. may have. Additionally, Mode 3 resonant frequencies (described below) may also or alternatively be known as or related to shear modes. SAW, S ₀ mode, extension mode, A ₁ mode, shear mode, and bending mode are well known in the art and will not be further described herein.

In the example, in a resonator body 4 having an optional bottom conductive layer 10 in the form of thin plate electrodes 33 and a top conductive layer 6 in the form of comb electrodes 27 with a finger pitch 38 of 1.4 μm, the resonator The body 4 may have modal resonant frequencies of Mode 1 resonant frequency = 1.79 GHz, Mode 2 resonant frequency = 2.88 GHz, and Mode 4 resonant frequency = 3.36 GHz. In the resonator body 4 of this example, the ratio of transverse mode resonance L out of the composite mode resonance can be L mode 1 = 70%, L mode 2 = 74% and L mode 4 = 35%.

By way of example, the foregoing description of a resonator body 4 resonating in thickness mode, transverse mode, or synthetic mode is combined with one or more connecting structures 34 and 36, described in more detail below. It may also be applicable to each UBAR 2 example shown in FIGS.

With continued reference to FIGS. 1-3, in one preferred and non-limiting embodiment or example, the bottommost layer of each resonator body 4 shown in FIGS. It can be mounted directly to carrier 14 using mounting techniques such as eutectic mounting, bonding, and the like. As used herein, “mounted directly,” “mounting directly” and similar phrases are used to refer to a carrier 14 positioned proximate to the carrier 14, in the example , mounting, mounting, etc. and/or in any suitable and/or desirable manner and/or example, by any suitable and/or desirable means such as eutectic bonding, conductive bonding, non-conductive bonding, etc. , is to be understood as the bottommost layer of each resonator body 4 shown in FIGS. In one preferred and non-limiting embodiment or example, carrier 14 can be the surface of a package, such as a conventional integrated circuit (IC) package. After the bottommost layer of the resonator body 4 has been mounted to the surface of the package, the resonator body 4 and more generally the UBAR 2 are encapsulated within the package in a manner well known in the art, The resonator body 4 and, more generally, the UBAR 2 can be protected against external environmental conditions. In an example, for example, NTK Ceramic Co. of Japan to implement UBAR. , Ltd. It is envisioned that a package such as a conventional ceramic IC package commercially available from Co., Inc. may be used. However, this is not to be interpreted in a limiting sense, as it is envisioned that the resonator body 4 and/or UBAR 2 may be mounted in any suitable and/or desired package now known or later developed. shall be

In another example, carrier 14 can be the surface of a substrate such as, for example, a sheet of ceramic, a sheet of conventional printed circuit board material, or the like. The description herein of example substrates on which the bottommost layer of each resonator body 4 and/or UBAR 2 shown in FIGS. shall be Rather, carrier 14 is compatible with the material forming the bottommost layer of each resonator body 4 and/or UBAR 2 shown in FIGS. It can be made of any suitable and/or desired material that enables the use of UBAR2. Carrier 14 can have any shape deemed suitable and/or desirable by those skilled in the art. Accordingly, any description of mounting substrate or carrier 14 herein is not to be construed in a limiting sense.

With continued reference to FIGS. 1-3, in one preferred and non-limiting embodiment or example, each UBAR 2 is provided with a top conductive layer 6 and an optional bottom conductive layer 10 of the resonator body 4. One or more optional connection structures 34 and/or 36 may be included to facilitate application of electrical signals thereto. However, in one preferred and non-limiting embodiment or example, an electrical signal can be applied directly to the top conductive layer 6 and optional bottom conductive layer 10 of the resonator body 4, if provided. Alternatively, optional connection structures 34 and/or 36 may be omitted (ie, not provided). Thus, in an example, UBAR 2 may comprise resonator body 4 without connecting structures 34 and 36 . In another example, UBAR 2 can comprise a resonator body 4 and a single connection structure 34 or 36 . For illustrative purposes only, in one preferred and non-limiting embodiment or example, a UBAR 2 comprising a resonator body 4 and connecting structures 34 and 36 is described.

Each connecting structure 34 and 36 may have any suitable and/or desired shape, may be formed in any suitable and/or desired manner, and may include top conductive layer 6 and optional bottom conductive layer 6 and optional bottom conductive layer. Layer 10 can be made of any suitable and/or desired material that, when provided, can facilitate the provision of separate electrical signals thereto. In the example, the top conductive layer 6 is in the form of a comb electrode 27 having only one rear surface 30 or 32 and the optional bottom conductive layer 10 is in the form of a comb electrode 27 having only one rear surface 30 or 32; or via a single connection structure 34 or 36 which, when in the form of a thin plate electrode 33, can be configured to provide separate electrical signals to the top conductive layer 6 and the optional bottom conductive layer 10. Electrical signals can be provided to each of the top conductive layer 6 and the optional bottom conductive layer 10 .

In another example, if at least one of top conductive layer 6 or optional bottom conductive layer 10 has the form of an interdigitated electrode 18 or interdigitated electrode 27 having two rear surfaces 30 and 32, one or Separate connection structures 34 and 36 may be provided to separately provide multiple electrical signals to the rear surfaces 24 and 26 of the interdigitated electrodes 18 and/or to the rear surfaces 30 and 32 of the comb electrodes 27 . The shape of top conductive layer 6 and optional bottom conductive layer 10, and the manner in which electrical signals are provided to top conductive layer 6 and optional bottom conductive layer 10, should not be interpreted in a limiting sense. and

While not wishing to be bound by any particular explanation, example, or theory, in one preferred and non-limiting embodiment or example, the UBAR2 example shown in FIGS. Examples of first and second connection structures 34 and 36 are described below.

In one preferred and non-limiting embodiment or example, for purposes of illustration only, each connection structure 34 and 36 is composed of various layers and layers forming the various examples of resonator bodies 4 shown in FIGS. /or described as having an extension of the substrate. However, this allows each connection structure 34 and 36 to provide one or more separate electrical signals to the top conductive layer 6 and optional bottom conductive layer 10 when provided. is not to be taken in a limiting sense, as it is envisioned that it can have any suitable and/or desired shape and/or structure of

In one preferred and non-limiting embodiment or example, see FIGS. 5A-5B, which can represent views along lines AA and BB in any one or all of FIGS. Referring to FIG. 5A, top conductive layer 6 in the form of comb electrodes 27 including rear surface 30 and optional rear surface 32 on top of piezoelectric layer 8 . In an example, the top conductive layer 6 can alternatively be in the form of interdigitated electrodes 18 . In one preferred and non-limiting embodiment or example, Figure 5B shows an optional bottom conductive layer 10 in the form of a thin plate electrode 33 below the piezoelectric layer 8 (shown in phantom in Figure 5B). In an example, the optional bottom conductive layer 10 can alternatively be in the form of interdigitated electrodes 18 or comb electrodes 27 . For the purposes of the following examples only, the top conductive layer 6 and the optional bottom conductive layer 10 are in the form of a comb electrode 18, including a rear surface 30 and an optional rear surface 32, and in the form of a thin plate electrode 33, respectively. described as a thing. However, this shall not be construed in a limiting sense.

In one preferred and non-limiting embodiment or example, connection structures 34 and 36 are bottom metal layers 40 and 44 ( 5B). Each bottom layer 40 and 44 can be in the form of a lamina covered by the piezoelectric layer 8 . In an example, each bottom layer 40 and 44 can be an extension of the thin plate electrode 33 and can be formed at the same time as the thin plate electrode 33 . In another example, each of bottom layers 40 and 44 can be formed separately from thin plate electrode 33 and can be made from the same or different material as thin plate electrode 33 . In the example, the connection structures 34 and 36 are on the top surface of the piezoelectric layer 8 and in contact with the rear surfaces 30 and 32, respectively, of the comb-teeth electrode 27 forming the top conductive layer 6 of the resonator body 4. Metal layers 42 and 46 may also be included.

In the example, bottom metal layers 40 and 44 are connected to first and second connection structures via conductive vias 50 formed in piezoelectric layer 8 extending between contact pads 48 and bottom metal layers 40 and 44. It can be connected to the contact pads 48 on the top surface of 34 and 36 . In an example, each top metal layer 42 and 46 may have the shape of a lamina spaced from the corresponding contact pad 48 by a gap (not numbered). Each top metal layer 42 and 46 may also include contact pads 58 . A suitable signal source (not shown) that each contact pad 48 can be used to electrically drive/energize the optional bottom conductive layer 10 in any suitable and/or desired manner, if desired. can be connected to Similarly, each contact pad 58 is connected to a suitable signal source (not shown) that can be used to drive/energize top conductive layer 6 in any suitable and/or desired manner, as needed. can be connected.

As indicated by reference numerals 18 and 27 in FIGS. 5A-5B, the top conductive layer 6 may alternatively be in the form of interdigitated electrodes 18 and the optional bottom conductive layer 10 may alternatively be in the form of combs. It can be in the form of tooth electrodes 27 or interdigitated electrodes 18 .

6A-6B, which can represent views along lines AA and BB in any one or all of FIGS. 1-3, one preferred and non-limiting embodiment or In the example, the example shown in FIGS. 6A-6B is similar to the example shown in FIGS. 5A-5B with at least the following exceptions. Bottom metal layers 40 and 44 are in the form of pairs of spaced-apart conductors 52 connected to optional bottom conductive layer 10 in the form of thin plate electrodes 33 by side conductors 54 and tether conductors 56, respectively (Figs. 5B). Top metal layers 42 and 46 may each be in the form of conductors 60 . Each conductor 60 may be connected to the rear surface 30 or 32 of the comb electrode 27 forming the top conductive layer 6 by a tether conductor 62 . Tether conductor 62 may be vertically aligned with tether conductor 56 and spaced therefrom by piezoelectric layer 8 . In an example, the width of tether conductor 62 can be less than the width of conductor 60, and the width of tether conductor 56 can be about the same as the width of tether conductor 62, as shown in FIGS. 6A-6B. .

7A-7B, which can represent views along lines AA and BB in any one or all of FIGS. 1-3, one preferred and non-limiting embodiment or In the example, the example shown in FIGS. 7A-7B is similar to the example shown in FIGS. 6A-6B with at least the following exceptions. Some or all of the material of each connection structure 34 and 36 on either side of the connection structure tether conductor 62 and tether conductor 56, if provided, may be removed, thereby removing the connection structure. A slot is formed that can extend some or all of the top-to-bottom distance of the UBAR 2 on each side of the tether conductor between the rest of the body and the resonator body 4 . The removal of some or all of the material of each connection structure 34 and 36 on either side of the tether conductor of said connection structure may, in the example, include tether conductor 62, tether conductor 56, if provided, and perpendicular to tether conductor 62. A tether structure 76 can be defined that can include a portion of the piezoelectric layer 8 aligned with the .

With reference to FIG. 7C, and with continued reference to FIGS. 7A-7B, in one preferred and non-limiting embodiment or example, the connecting structure tether conductor 62 and tether conductor 56, if provided, Removal of some or all of the material forming each connecting structure 34 and 36 on both sides can be used in any of the examples of UBARs 2 shown in FIGS. 1-3. For example, FIG. 7C illustrates first and second connection structures 34 and 56 on each side of each said connection structure, tether conductor 62 and tether conductor 56, if provided, as shown in FIGS. 7A-7B. 2 shows a side view of the example UBAR 2 shown in FIG. 1 with 36 material removed; FIG. As can be seen from FIGS. 7A-7C, the removed material of each connecting structure on either side of tether conductor 62 and tether conductor 56, if any, is the top conductive layer 6 and the piezoelectric layer. 8, the optional bottom conductive layer 10, if provided, and a portion of the device layer 12, so that in the views shown in FIGS. , on either side of tether conductor 56, if present, in the slots formed by the removal of these materials in each connection structure 34 and 36. 7A-7C, each tether structure 76 includes, from top to bottom, tether conductor 62, a portion of piezoelectric layer 8 aligned perpendicular to tether conductor 62, and optional tether conductor 56 (bottom surface). conductive layer 10 when present) and a portion of device layer 12 vertically aligned with tether conductor 62 .

In another example, UBAR 2 is shown in phantom in FIG. 7C with substrate 16 (FIG. 2) and optionally one or more additional device layers 12-1 and/or substrate 16-1 (FIG. 3). , substrate 16 and each additional device layer 12-1 and/or substrate 16-1 of each connection structure 34 and 36 on either side of tether conductor 62 and tether conductor 56, if provided. The material forming them, if present, may also be removed, so that in the views shown in FIGS. , no material should be visible in the slots formed by the removal of these materials in each connecting structure 34 and 36 .

By way of example, if the views shown in FIGS. 7A-7B are the example of UBAR 2 shown in FIG. 8, an optional tether conductor 56 (when optional bottom conductive layer 10 is present), a portion of device layer 12 aligned perpendicular to tether conductor 62, and a portion of device layer 12 perpendicular to and a portion of the substrate 16 aligned with the . In another example, if the views shown in FIGS. 7A-7B are the example of UBAR 2 shown in FIG. A portion of the piezoelectric layer 8, an optional tether conductor 56 (when the optional bottom conductive layer 10 is present), a portion of the device layers 12 and 12-1 vertically aligned with the tether conductor 62, and a tether. and portions of substrates 16 and 16-1 vertically aligned with conductors 62. FIG.

8A-8B, which can represent views along lines AA and BB in any one or all of FIGS. 1-3, one preferred and non-limiting embodiment or In the example, the example shown in FIGS. 8A-8B is similar to the example shown in FIGS. 7A-7B with at least the following exceptions. That is, the material forming all or part of at least one device layer 12 or 12-1 of each connection structure 34 and 36 is the same as the tether conductor 62 and, if provided, the tether conductor 56 of said connection structure. so that the material of the at least one device layer 12 or 12-1 is placed in the slots of the connection structure on both sides of the tether conductor 62 and the tether conductor 56, if provided. appear. By way of example, if the views shown in FIGS. 8A-8C are the example of UBAR 2 shown in FIG. 8 and optional tether conductor 56 (when optional bottom conductive layer 10 is present). In this example, the device layer 12 should be retained and visible in the slots shown in FIGS. 8A-8B.

In another example, if the views shown in FIGS. 8A-8B are the example of UBAR 2 shown in FIG. It may include a portion of piezoelectric layer 8 , optional tether conductor 56 (when optional bottom conductive layer 10 is present), and a portion of device layer 12 vertically aligned with tether conductor 62 . In this example, the device layer 12 should be retained and visible in the slots shown in FIGS. 8A-8B, while the substrate 16 (shown in phantom in FIG. 8C) underneath the device layer 12 is still retained. , should not be visible in the slots shown in FIGS. 8A-8B.

In another example, if the views shown in FIGS. 8A-8B are the example of UBAR 2 shown in FIG. It may include a portion of piezoelectric layer 8 , optional tether conductor 56 (when optional bottom conductive layer 10 is present), and a portion of device layer 12 vertically aligned with tether conductor 62 . In an example, if the device layer 12 is held and visible in the slot shown in FIGS. 8A-8B, the substrate 16 underneath the device layer 12 is still held but visible in the slot shown in FIGS. 8A-8B. Each tether structure 76 would also include a portion of device layer 12 - 1 and a portion of substrate 16 - 1 vertically aligned with tether conductor 62 . In another example, if device layer 12-1 is retained and visible within the slots shown in FIGS. It should not be visible in the slot shown.

In another example shown in FIG. 8D, in the UBAR 2 example shown in FIG. a portion, an optional tether conductor 56 (when the optional bottom conductive layer 10 is present), and each connecting structure 34 and 36 on both sides of the tether conductor 62 and tether conductor 56, if provided; and a portion of the body of device layer 12 vertically aligned with tether conductors 62 exposed by partial removal of device layer 12 . If the example shown in Figure 8D is the UBAR 2 shown in Figure 2, the substrate 16 (shown in phantom in Figure 8D) would be held below the device layer 12 and not visible in the views shown in Figures 8A-8B. be.

In another example, in the UBAR 2 example shown in FIG. 3, each tether structure 76 includes, from top to bottom, a tether conductor 62, a portion of piezoelectric layer 8 vertically aligned with tether conductor 62, and an optional tether conductor 56 (when optional bottom conductive layer 10 is present) and device layer 12 or 12 of each connection structure 34 and 36 on either side of tether conductor 62 and tether conductor 56, if present. -1 (similar to the partial removal of device layer 12 shown in FIG. 8D) and a portion of the body of device layer 12 or device layer 12-1 vertically aligned with tether conductors 62 exposed. be able to. In an example, a portion of the body of device layer 12 of UBAR2 shown in FIG. 3 is removed (similar to the partial removal of device layer 12 shown in FIG. 8D), thereby forming device layer 12 of UBAR2 shown in FIG. A portion of the interior of the material can be seen in the slots shown in FIGS. 8A-8B, and each tether structure 76 can also include portions of device layer 12-1 and substrate 16-1 vertically aligned with tether conductors 62. can. In this example, the substrate 16 is retained, ie, no portion of the substrate 16 is removed and should not be visible in the views shown in FIGS. 8A-8B.

In another example, a portion of the body of device layer 12-1 of UBAR2 shown in FIG. 3 is removed (similar to the partial removal of device layer 12 shown in FIG. 8D), thereby forming device layer 12-1. A portion of the interior of the material is visible in the slots shown in FIGS. 8A-8B, and each tether structure 76 can also include a portion of the body of device layer 12-1 vertically aligned with tether conductor 62. FIG. In this example, substrates 16 and 16-1 and device layer 12 are retained, ie substrates 16 and 16-1 and device layer 12 are not removed and are not visible in the views shown in FIGS. 8A-8B. should be.

9A-9B, which can represent views along lines AA and BB in any one or all of FIGS. 1-3, the UBAR2 shown in FIG. In a non-limiting embodiment or example, the example shown in FIGS. 9A-9B is similar to the example shown in FIGS. 8A-8B with at least the following exceptions. Each tether structure 76 can include a portion of the material forming device layer 12 such that, in the views shown in FIGS. 62 and in slots formed on either side of tether conductor 56, if provided. In this example, substrate 16 is held and each tether structure 76 includes, from top to bottom, tether conductor 62, a portion of piezoelectric layer 8 aligned perpendicular to tether conductor 62, and optional tether conductor 56 ( optional bottom conductive layer 10 when present) and a portion of device layer 12 vertically aligned with tether conductors 62 .

With continued reference to FIGS. 9A-9B, in one preferred and non-limiting embodiment or example, the UBAR 2 shown in FIG. 2, substrate 16-1 can be seen in the slots formed on both sides of tether conductor 62 and tether conductor 56, if provided, of each connection structure 34 and 36. In FIG. In this example, each tether structure 76 includes, from top to bottom, tether conductor 62, a portion of piezoelectric layer 8 aligned perpendicular to tether conductor 62, and optional tether conductor 56 (optional bottom conductive layer 10 when present) and a portion of device layer 12-1 vertically aligned with tether conductor 62. FIG.

In another example, in the UBAR 2 shown in FIG. 3, the substrate 16 is held so that in the views shown in FIGS. Each tether structure 76, if provided and visible in slots formed on either side of it, each tether structure 76 includes, from top to bottom, a tether conductor 62 and a portion of the piezoelectric layer 8 vertically aligned with the tether conductor 62. , optional tether conductor 56 (when optional bottom conductive layer 10 is present), a portion of device layer 12-1 vertically aligned with tether conductor 62, and a portion of device layer 12-1 vertically aligned with tether conductor 62. and a portion of the device layer 12 vertically aligned with the tether conductors 62 .

In another example shown in FIG. 9D, in the UBAR 2 example shown in FIG. and 36, so that bottom portions 64 and 70 of connection structures 34 and 36 are exposed and bottom portions 66 and 68 of resonator body 4 are exposed, as shown in FIG. 9D. are exposed, and surfaces 72 and 74 of the body of substrate 16 are exposed. In this example, the removed portion of the material forming the body of substrate 16 can extend into the plane of FIG. In this example, each tether structure 76 includes, from top to bottom, tether conductor 62, a portion of piezoelectric layer 8 aligned perpendicular to tether conductor 62, and optional tether conductor 56 (optional bottom conductive layer 10), a portion of the device layer 12 vertically aligned with the tether conductors 62, and a portion of the substrate 16 proximate a portion of the device layer 12 and vertically aligned with the tether conductors 62. can contain. In this example, surfaces 72 and 74 can be seen within the slots shown in FIGS. 9A-9B.

In another alternative, in the UBAR 2 example shown in FIG. 3, a portion of the material forming substrate 16-1 or 16 may be removed from the resonator body 4 as well as the connections, similar to the removal of the material forming substrate 16 in FIG. 9D. It can be removed laterally beneath structures 34 and 36, thereby exposing surfaces (such as surfaces 72 and 74) of the material forming substrate 16-1 or 16, leaving the slots shown in FIGS. 9A-9B. can be seen inside.

In an example, surfaces (such as surfaces 72 and 74) of the material forming substrate 16-1 of the UBAR2 example of FIG. 3 may be exposed and visible within the slots shown in FIGS. including a portion of device layer 12-1 vertically aligned with conductor 62 and a portion of material forming substrate 16-1 vertically aligned with tether conductor 62 proximate device layer 12-1. can also In this example, only a portion of the body of substrate 16-1 is removed to form each slot and device layer 12 and substrate 16 are retained, i.e., device layer 12 and substrate 16 have no portion removed. , are not visible in the views shown in FIGS. 9A-9B.

In another example, surfaces (such as surfaces 72 and 74) of the material forming substrate 16 of the UBAR2 example of FIG. 3 can be exposed and visible within the slots shown in FIGS. A portion of device layer 12-1 vertically aligned with conductor 62, a portion of substrate 16-1 vertically aligned with tether conductor 62, and a portion of device layer 12 vertically aligned with tether conductor 62. It can also include a portion and a portion of the material forming substrate 16 proximate device layer 12 and vertically aligned with tether conductors 62 . In this example, only a portion of the body of substrate 16 is removed to form each slot.

In one preferred and non-limiting embodiment or example, in any of the examples discussed above, where bottom conductive layer 10 is absent, bottom metal layers 40 and 44 of connecting structures 34 and 36 are: May not exist.

In one preferred and non-limiting embodiment or example, each tether structure 76 described above includes at least tether conductor 62 and optional tether conductor 56 (when optional bottom conductive layer 10 is present). , and only a portion of the piezoelectric layer 8 that is vertically aligned with the tether conductor 62 . In another preferred and non-limiting embodiment or example, each tether structure 76 includes device layer 12, substrate 16, device layer 16-1, and/or substrate 16-1 aligned perpendicular to tether conductor 62. It can also include only a portion of one or more of 1. However, this shall not be construed in a limiting sense.

In one preferred and non-limiting embodiment or example, each example resonator body 4 shown in FIGS. The width of the portion of the piezoelectric layer 8 below the conductive layer 6 may all be the same. Also, or alternatively, in an example, the width and/or dimensions of device layer 12, substrate 16, and device layer 12-1 and/or substrate 16-1, if provided, are all equal to the top conductive layer. 6, the optional bottom conductive layer 10 if present, and the piezoelectric layer 8 in width and/or dimensions.

In one preferred and non-limiting embodiment or example, any one or more of the example surfaces of any resonator body 4 shown in FIGS. If connection structures 34 and/or 36 are provided, one or all of their surfaces may be etched as deemed appropriate and/or desirable to provide any UBAR 2 example shown in FIGS. can be optimized for quality factor and/or insertion loss. For example, the top and bottom surfaces of any of the example resonator bodies 4 shown in FIGS. 1-3 can be etched. Also, or alternatively, one or more side surfaces of any of the examples of resonator body 4 shown in FIGS. 1-3 may be etched so that each of said side surfaces is vertically planar. can be done.

In one preferred and non-limiting embodiment or example, if a top conductive layer 6, or an optional bottom conductive layer 10 is provided, or if the bottom conductive layer 10, or both are in the form of interdigitated electrodes 18, One rear surface 22 or 26 of the interdigitated electrodes 18 can be connected to and driven by a suitable signal source, while the other rear surface 22 or 26 is connected to a signal source. can not. In another preferred and non-limiting embodiment or example, if a top conductive layer 6, or an optional bottom conductive layer 10 is provided, the bottom conductive layer 10, or if both are in the form of interdigitated electrodes 18, The rear surface 22 of the interdigitated electrodes 18 can be connected to and driven by one signal source, the rear surface 26 of the interdigitated electrodes 18 is connected to a second signal source, It can be driven by a second signal source. In examples, the second signal source can be the same or different than the first signal source.

In one preferred and non-limiting embodiment or example, each instance of element layer 12 (or 12-1) can have an acoustic impedance of 60×10 ⁶ Pa·s/m ³ or greater. In another example, each embodiment of device layer 12 (or 12-1) can have an acoustic impedance of 90×10 ⁶ Pa·s/m ³ or greater. In another example, each embodiment of device layer 12 (or 12-1) can have an acoustic impedance of 500×10 ⁶ Pa·s/m ³ or greater. In one preferred and non-limiting embodiment or example, each substrate layer 16 can have an acoustic impedance of 100×10 ⁶ Pa·s/m ³ or less. In another example, each substrate layer 16 can have an acoustic impedance of 60×10 ⁶ Pa·s/m ³ or less.

In one preferred and non-limiting embodiment or example, the acoustic wave reflectance (R) at the interface between the device layer 12 and the piezoelectric layer 8 or optional bottom conductive layer 10, if provided, is 50%. can be super. In another example, the reflectivity (R) of acoustic waves at the interface between the device layer 12 and the piezoelectric layer 8 or optional bottom conductive layer 10, if provided, can be greater than 70%. In another example, the reflectivity (R) of acoustic waves at the interface between the device layer 12 and the piezoelectric layer 8 or optional bottom conductive layer 10, if provided, can be greater than 90%.

In one preferred and non-limiting embodiment or example, the acoustic wave reflectance (R) at the interface between the element layer 12 or 12-1 and the piezoelectric layer 8 or the optional bottom conductive layer 10, if provided can be greater than 70%. In an example, at the interface between any two layers 6 and 8, 8 and 10, 8 or 10 and 12 or 12-1, or 12 or 12-1 and 16 or 16-1, or device layer 12 Alternatively, the reflectance R at the interface between 12-1 and substrate 16 or 16-1 can be obtained by the following formula.

R=|(Zb−Za)/(Za+Zb)|

where Za = the acoustic impedance of the first layer, e.g. the piezoelectric layer 8 or the bottom conductive layer 10 if an optional bottom conductive layer 10 located above the second layer is provided;

Zb=acoustic impedance of the second layer, eg device layer 12;

Other examples of first and second layers can include embodiments of device layer 12 or 12-1 on substrate 16 or 16-1.

In one preferred and non-limiting embodiment or example, the total reflectance (R) of any example resonator body 4 shown in FIGS. 1-3 can be >90%.

In one preferred and non-limiting embodiment or example, device layer 12 can be a layer of diamond or SiC formed in a manner well known in the art. In an example, substrate 16 can be formed from silicon.

In one preferred and non-limiting embodiment or example, the diamond formed device layer 12 is formed by chemical vapor deposition (CVD) of diamond on substrate 16 or 16-1 or a sacrificial substrate (not shown). can be grown by In one preferred and non-limiting embodiment or example, the optional bottom conductive layer 10, piezoelectric layer 8, and top conductive layer 6 are formed using conventional semiconductor processing techniques not further described herein. , can be deposited on the device layer 12 and patterned as desired (eg, comb electrodes 27 or interdigitated electrodes 18).

As used herein, each temperature compensating layer 90, 92, and 94 may include at least one of silicon and oxygen. For example, each temperature compensating layer can include silicon dioxide, or elemental silicon, and/or elemental oxygen.

In one preferred and non-limiting embodiment or example, each UBAR 2 shown in FIGS. 1-3 can have an unloaded quality factor of 100 or more. In another example, each UBAR 2 shown in FIGS. 1-3 may have an unloaded quality factor of 50 or greater. In one preferred and non-limiting embodiment or example, the piezoelectric layer 8, each element layer 12, and each substrate 16 of the example resonator body 4 shown in FIGS. The thickness can be selected in any suitable and/or desired manner to optimize the performance of the resonator body 4. Similarly, in an example, the example dimensions of each resonator body 4 shown in FIGS. 1-3 can be selected for target performance such as insertion loss, power handling capability, and heat dissipation, without limit. In one preferred and non-limiting embodiment or example, when diamond is used as the material for device layer 12, the surface of said diamond layer at the interface with bottom layer 12 is optically finished and/or physically can be densified to In an example, the diamond material forming device layer 12 can be undoped or doped, eg, P-type or N-type. The diamond material can be polycrystalline, nanocrystalline, or ultra-nanocrystalline. By way of example, when silicon is used as the material for each embodiment of substrate 16, said silicon may be undoped or doped, e.g., P-type or N-type, monocrystalline or polycrystalline. can be. The diamond material forming the device layer can have a Raman half-width of 20 cm ⁻¹ or less.

In one preferred and non-limiting embodiment or example, the piezoelectric layer 8 is ZnO, AlN, InN, alkali metal or alkaline earth metal niobates, alkali metal or alkaline earth metal titanates, alkali metal or alkaline earth metal It can be formed of tantalite, GaN, AlGaN, lead zirconate titanate (PZT), polymers or doped forms of any of the aforementioned materials.

In one preferred and non-limiting embodiment or example, element layer 12 can be formed of any suitable and/or desired high acoustic impedance material. In an example, a material with an acoustic impedance between 10 ⁶ Pa·s/m ³ and 630×10 ⁶ Pa·s/m ³ or higher can be considered a high acoustic impedance material. For example, some non-limiting examples of typical high acoustic impedance materials that can be used to form any device layer 12 described herein include diamond (approximately 630×10 ⁶ Pa·s /m ³ ); W (about 99.7×10 ⁶ Pa·s/m ³ ); SiC; condensed phase materials such as metals, such as Al, Pt, Pd, Mo, Cr, Ir, Ti, Ta; Elements from groups 3A or 4A of the table; transition elements from groups 1B, 2B, 3B, 4B, 5B, 6B, 7B, or 8B of the periodic table; ceramics; glasses, and polymers. This listing of non-limiting examples of high acoustic impedance materials is not to be construed in a limiting sense.

In one preferred and non-limiting embodiment or example, substrate 16 can be formed of any suitable and/or desired low acoustic impedance material. In an example, materials with acoustic impedances between 10 ⁶ Pa·s/m ³ and 30×10 ⁶ Pa·s/m ³ can be considered low acoustic impedance materials. For example, some non-limiting examples of typical low acoustic impedance materials that can be used to form any of the substrates ¹⁶ described herein ^include ceramics; glasses, crystals, minerals and metals with acoustic impedances between 30×10 ⁶ Pa·s/m ³ ; ivory (1.4×10 ⁶ Pa·s/m ³ ); alumina/sapphire (25.5× 10 ⁶ Pa·s/m ³ ); alkali metal K (1.4×10 ⁶ Pa·s/m ³ ); SiO ₂ and silicon (19.7×10 ⁶ Pa·s/m ³ ). At least one may be included. This listing of non-limiting examples of low acoustic impedance materials is not to be construed in a limiting sense.

In one preferred and non-limiting embodiment or example, the choice of materials forming each instance of the resonator body 4 causes one or more materials typically considered high acoustic impedance materials to be It can function as a low acoustic impedance material for the body 4 . For example, if diamond or SiC is used as the device layer 12 material, W can be used as the substrate 16 material. Therefore, by achieving the desired reflectance R (discussed above) at the interface of the two layers or substrates of the resonator body 4, which materials can be used as high acoustic impedance materials and which materials can be used as low acoustic impedance materials. can be used as

In one preferred and non-limiting embodiment or example, a bulk acoustic resonator according to the principles of the invention can include a resonator body 4. As shown in FIG. The resonator body 4 may include a piezoelectric layer 8 , an element layer 12 and a top conductive layer 6 on the piezoelectric layer 8 opposite the element layer 12 . Substantially all of the surface of the element layer 12 opposite the piezoelectric layer is for mounting the resonator body 4 on a carrier 14 which is separate from the resonator body 4 . In an example, all of the surface of the element layer opposite the piezoelectric layer can be for mounting the entire resonator body to the carrier, although this is not essential. In an example, the bulk acoustic resonator may desirably, but not necessarily, include connection structures 34 or 36 to conduct signals to the top conductive layer. In examples, the device layer can include diamond or SiC. In an example, the top conductive layer 6 can include a plurality of spaced-apart conductive lines or fingers. In an example, the resonator body 4 can further comprise an optional bottom conductive layer 10 between the piezoelectric layer 8 and the device layer 12 .

In one preferred and non-limiting embodiment or example, the resonator body 4 can further include a substrate 16 attached to the device layer 12 opposite the piezoelectric layer 8 . In an example, the surface of device layer 12 can be mounted in its entirety to substrate 16 . In an example, the surface of substrate 16 facing carrier 14 may be for direct mounting of the entirety thereof to carrier 14 .

In one preferred and non-limiting embodiment or example, the surface of device layer 12 facing carrier 14 can be directly mounted to substrate 16 in its entirety. In the example, the surface of device layer 12 facing carrier 14 is for direct mounting of the entirety thereof to carrier 14 .

In one preferred and non-limiting embodiment or example, the resonator body 4 includes a second element layer 12-1 between the substrate 16 and the piezoelectric layer 8, or a second element layer 12-1 between the substrate 16 and the piezoelectric layer 8. can further include a second substrate 16-1, or both.

In one preferred and non-limiting embodiment or example, as used herein, "mounting in its entity" means that one layer or substrate directly or indirectly can be meant to be implemented in By way of example, as used herein, "mounting in its entity" also, or alternatively, intentionally mounts between one layer or substrate and another layer or substrate. It can mean that there are no introduced spaces or gaps. In another example, as used herein, "mounting in its entirety" also or alternatively means the natural structure between one layer or substrate and another layer or substrate. It can include naturally occurring spaces that can be (but not intentionally) formed into.

Having thus described several non-limiting embodiments or examples of UBAR, first through sixth examples of UBAR are now described.

First Example of UBAR: Device Layer Effective Mode 3 and/or Mode 4 Resonance with the Presence of a Temperature Compensating Layer

Referring back to FIG. 1, in some non-limiting embodiments or examples, a first example of UBAR 2 (shown in FIG. 1) extends from its top surface to carrier 14 with spaced-apart conductive lines or It comprises a finger 20 or 28 (shown in FIGS. 4A-4B), piezoelectric layer 8 made of LiNbO ₃ , temperature compensation layer 92 made of SiO ₂ and device layer 12 made of diamond or SiC. A top conductive layer 6 may be included. In the example, the finger pitch 38 (shown in FIGS. 4A-4B) is 0.6 μm and the thickness of the piezoelectric layer 8 is 0.6 μm.

Throughout this disclosure, the value of variable “λ” can be based on one or more dimensions of the pattern or features defined by top conductive layer 6 or based on the thickness of piezoelectric layer 8 . In some non-limiting embodiments or examples, the value of λ may be equal to twice the finger pitch 38 or twice the thickness of the piezoelectric layer 8 (1.2 μm in this example). may be equal to However, the value of λ may be any other suitable and/or desirable dimension and/or thickness of one or more layers of one or more other patterns or features of each UBAR example described herein. This shall not be interpreted in a limiting sense as it may be based on thickness. In this example, the cut angle of the piezoelectric layer 8 was 0° (or 180°), sometimes called Y-cut or YX-cut. In some non-limiting embodiments or examples, use of a cut angle of piezoelectric layer 8 of 0° (or 180°) ±20° is envisioned. Herein, unless otherwise indicated, the cut angles of the piezoelectric layer 8 are referenced to the cut angles rotated about the X-axis.

In some non-limiting embodiments or examples, to model the first example of UBAR2, the frequency response (frequency vs. amplitude) is scaled with the thickness of the temperature compensation layer 92 made of _SiO2 . A frequency sweep (eg, from 1 GHz to 6.2 GHz) of an exemplary electrical stimulus applied to this first example of UBAR2 was determined for one or more different exemplary values. In a modeling example, the thickness of temperature-compensating layer 92 made of SiO ₂ is varied between (9/16)λ and (1/64)λ, and the first The frequency of the exemplary electrical stimuli applied in the examples varied between at least 1 GHz and 6.2 GHz. In an example, a first plot, graph, or relationship of frequency versus amplitude, e.g. asked. In the example, another plot, graph, or relationship of frequency versus amplitude was obtained for a frequency sweep between at least 1 GHz and 6.2 GHz for a thickness of temperature-compensating layer 92 of, for example, (3/64)λ. . Additional plots, graphs, or relationships of frequency versus amplitude were obtained for frequency sweeps of other thicknesses of temperature-compensating layer 92 .

At least a Mode 4 resonance frequency 88 (FIGS. 10 and 11) was observed for each plot, graph or relationship of frequency versus amplitude. However, in this first example of UBAR, unexpectedly, the Mode 4 resonance frequency 88 is observed at about 5.2 GHz, as opposed to 3.05 GHz for the Mode 4 resonance frequency 88 shown in FIG. 10 (FIG. 11). , a mode 3 resonance frequency 86 (FIG. 11) was observed at about 3.13 GHz.

In FIG. 11, Mode 1 and Mode 2 resonance frequencies 82 and 84 (eg, shown in FIG. 10) are omitted to the left of Mode 3 resonance frequency 86 for clarity. However, at least for frequency sweeps between 1 GHz and 6.2 GHz, Mode 1 and Mode 2 resonant frequencies 82 and 84 (eg, shown in FIG. 10) are present in addition to Mode 3 and Mode 4 resonant frequencies 86 and 88. It should be understood that

In some non-limiting embodiments or examples, for example, as shown in FIG. 11, frequency versus amplitude plots, graphs, or relationships show a positive peak value of f _s1 at mode 3 resonance frequency 86 and f at the mode 4 resonance frequency 88, including the positive peak _value of _fs2 and the negative peak value of _fp2 .

For descriptive purposes only, a “resonant frequency” observed “for” a particular frequency is defined herein as the mode 3 resonant frequency 86 between the peak positive value f _s1 and the peak negative value of f _p1 . , and mode 4 resonance frequency 88 can be any representative frequency between the positive peak value _fs2 and the negative peak value of _fp2 . Accordingly, any resonant frequency described herein as being “related to” a particular frequency shall not be construed in a limiting sense.

In some non-limiting embodiments or examples, the mode ₃ coupling of mode 3 and mode 4 resonance frequencies 86 and 88 is Efficiency (M3CE) and mode 4 coupling efficiency (M4CE) can be determined by the following equations EQ1 and EQ2, respectively.
EQ1: Mode 3 coupling efficiency (M3CE)=(π ² /4)((f _p1 −f _s1 )/f _p1 )
EQ2: Mode 4 coupling efficiency (M4CE) = (π ² /4) ((f _p2 - f _s2 )/f _p2 )
where for exemplary values of f _p1 and f _s1 equal to 3.738 GHz and 3.13 GHz, respectively,
M3CE=40.093%, and for exemplary values of _fp2 and _fs2 equal to 5.442 GHz and 5.172 GHz, respectively,
M4CE = 12.229%

However, the aforementioned values of M3CE in this example may be satisfactory, suitable and/or desirable for values of M3CE of 8% or greater, 11% or greater, 14% or greater, 17% or greater, or 20% or greater. Therefore, it shall not be construed in a limiting sense. Also, or alternatively, the foregoing values of M4CE in this example are such that values of M4CE of 3% or greater, 4% or greater, 6% or greater, 8% or greater, or 10% or greater are satisfactory, suitable and/or or may be desirable and shall not be construed in a limiting sense.

In some non-limiting embodiments or examples, when specific values of M3CE are desired, e.g., 8% or more, 11% or more, 14% or more, 17% or more, or 20% or more, the piezoelectric layer 8 cut angles exceed the above cut angles of 0° (or 180°) ± 20°, for example, 0° (or 180°) ± 20° or more, ± 30° or more, ± 40° or more, ± Cut angles can range, such as 50° or more. In some non-limiting embodiments or examples, without limitation, a piezoelectric layer 8 such as a _LiNbO3 crystal fabricated from a desired cut angle of Z-cut or X-cut to obtain a desired specific value of M3CE. may also be sufficient for

In some non-limiting embodiments or examples, when some level of M4CE is desired, e.g., 3% or more, 4% or more, 6% or more, 8% or more, or 10% or more, The cut angle exceeds a cut angle of 130° ± 30° (sometimes called Y cut 130 ± 30 or YX cut 130 ± 30), for example, 130° ± 30° or more, ± 40° or more, ± 50 It can span cut angles such as ° or more. In some non-limiting embodiments or examples, without limitation, a piezoelectric layer 8 such as a _LiNbO3 crystal fabricated from a desired cut angle of Z-cut or X-cut to obtain the desired specific value of M4CE may also be sufficient for

In some non-limiting embodiments or examples, frequency versus amplitude plots, graphs, or Using the relationship, the thickness values of the temperature-compensating layer 92 made of _SiO2 that optimize the mode 3 and mode 4 resonance frequencies are (3/64)λ and (1/32)λ, respectively. was decided. However, these thickness values are 1λ or less, (1/2)λ _or less, (3 It should not be construed in a limiting sense as it may be of thickness such as /8)λ or less, (1/4)λ or less, or (1/8)λ or less.

Second UBAR Example: Device Layer Effective Mode 3 and/or Mode 4 Resonance Without the Presence of a Temperature Compensating Layer

In some non-limiting embodiments or examples, for purposes of comparison and/or modeling, the frequency response is in most respects described above except that the second example of UBAR2 excludes the temperature compensation layer 92. was determined for an exemplary electrical stimulation frequency sweep (e.g., from 1 GHz to 6.2 GHz) applied to a second example of UBAR2 similar to the first example of UBAR2 described in (shown in FIG. 1). . A frequency versus amplitude plot, graph, or relationship was obtained for the frequency sweep.

Utilizing equations EQ1 and EQ2 and frequency vs. amplitude plots, graphs or relationships determined for frequency sweeps, the coupling efficiencies M3CE and M4CE for the mode 3 and mode 4 resonance frequencies 86 and 88 of the second example of UBAR2 are: It was determined to be the following values:
M3CE=40.093% for values of f _p1 and f _s1 equal to 3.738 GHz and 3.13 GHz, respectively
and M4CE=9.312% for values of f _p2 and f _s2 equal to 6.194 GHz and 5.96 GHz, respectively

However, the aforementioned values of M3CE in this example may be satisfactory, suitable and/or desirable for values of M3CE of 8% or greater, 11% or greater, 14% or greater, 17% or greater, or 20% or greater. Therefore, it shall not be construed in a limiting sense. Also, or alternatively, the foregoing values of M4CE in this example are such that values of M4CE of 3% or greater, 4% or greater, 6% or greater, 8% or greater, or 10% or greater are satisfactory, suitable and/or or may be desirable and shall not be construed in a limiting sense.

In some non-limiting embodiments or examples, when specific values of M3CE are desired, e.g., 8% or more, 11% or more, 14% or more, 17% or more, or 20% or more, the piezoelectric layer 8 cut angles exceed the above cut angles of 0° (or 180°) ± 20°, for example, 0° (or 180°) ± 20° or more, ± 30° or more, ± 40° or more, ± Cut angles can range, such as 50° or more. In some non-limiting embodiments or examples, without limitation, a piezoelectric layer 8 such as a _LiNbO3 crystal fabricated from a desired cut angle of Z-cut or X-cut to obtain a desired specific value of M3CE. may also be sufficient for

In some non-limiting embodiments or examples, when some level of M4CE is desired, e.g., 3% or more, 4% or more, 6% or more, 8% or more, or 10% or more, The cut angle exceeds a cut angle of 130° ± 30° (sometimes called Y cut 130 ± 30 or YX cut 130 ± 30), for example, 130° ± 30° or more, ± 40° or more, ± 50 It can span cut angles such as ° or more. In some non-limiting embodiments or examples, without limitation, a piezoelectric layer 8 such as a _LiNbO3 crystal fabricated from a desired cut angle of Z-cut or X-cut to obtain the desired specific value of M4CE may also be sufficient for

As can be seen from the values of M4CE for UBAR2 with and without temperature-compensating layer 92 discussed above, the coupling efficiency may be greater for UBAR2 with temperature-compensating layer 92 of _SiO2 and vice versa. Additionally, the coupling efficiency may be lower for UBAR 2 that does not have a temperature compensation layer 92 of SiO ₂ . In some non-limiting embodiments or examples, higher values of coupling efficiency are generally more desirable.

Third example of UBAR: device layer effective mode 3 and/or mode 4 resonance with the presence of a temperature compensation layer and a layer of aluminum nitride

12, and with continued reference to FIG. 11, in some non-limiting embodiments or examples, for purposes of comparison and/or modeling, the frequency response is measured with at least the following exceptions: A third example includes a layer of AlN 96 between the diamond or SiC device layer 12 and a temperature compensation layer 92 of SiO ₂ shown in FIG. )λ, the temperature compensation layer 92 of SiO ₂ has a thickness of (11/128)λ, and the device layer 12 made of diamond or SiC has a thickness of (90/16) A frequency sweep of an exemplary electrical stimulus applied to a third example of UBAR2 (shown in FIG. 12) that is similar in most respects to the first example of UBAR2 described above, except that it has λ (eg, from 1 GHz to 6.2 GHz). In this example λ is equal to 1.6 μm. A frequency versus amplitude plot, graph, or relationship was obtained for the frequency sweep.

Utilizing equations EQ1 and EQ2 and frequency vs. amplitude plots, graphs or relationships determined for frequency sweeps, the coupling efficiency M3CE for mode 3 and mode 4 resonance frequencies 86 and 88 of the third example of UBAR2 shown in FIG. and M4CE were determined to be the following values:
M3CE=39.351% for values of f _p1 and f _s1 equal to 3.608 GHz and 3.032 GHz, respectively
and M4CE=10.802% for values of f _p2 and f _s2 equal to 5.02 GHz and 4.8 GHz, respectively

However, the aforementioned values of M3CE in this example may be satisfactory, suitable and/or desirable for values of M3CE of 8% or greater, 11% or greater, 14% or greater, 17% or greater, or 20% or greater. Therefore, it shall not be construed in a limiting sense. Also, or alternatively, the foregoing values of M4CE in this example are such that values of M4CE of 3% or greater, 4% or greater, 6% or greater, 8% or greater, or 10% or greater are satisfactory, suitable and/or or may be desirable and shall not be construed in a limiting sense.

In some non-limiting embodiments or examples, when specific values of M3CE are desired, e.g., 8% or more, 11% or more, 14% or more, 17% or more, or 20% or more, the piezoelectric layer 8 cut angles exceed the above cut angles of 0° (or 180°) ± 20°, for example, 0° (or 180°) ± 20° or more, ± 30° or more, ± 40° or more, ± Cut angles can range, such as 50° or more. In some non-limiting embodiments or examples, without limitation, a piezoelectric layer 8 such as a _LiNbO3 crystal fabricated from a desired cut angle of Z-cut or X-cut to obtain a desired specific value of M3CE. may also be sufficient for

In some non-limiting embodiments or examples, when some level of M4CE is desired, e.g., 3% or more, 4% or more, 6% or more, 8% or more, or 10% or more, The cut angle exceeds a cut angle of 130° ± 30° (sometimes called Y cut 130 ± 30 or YX cut 130 ± 30), for example, 130° ± 30° or more, ± 40° or more, ± 50 It can span cut angles such as ° or more. In some non-limiting embodiments or examples, without limitation, a piezoelectric layer 8 such as a _LiNbO3 crystal fabricated from a desired cut angle of Z-cut or X-cut to obtain the desired specific value of M4CE may also be sufficient for

In the above examples of the first through third examples of UBAR, M3CE and M4CE were determined for piezoelectric layer 8 formed of LiNbO ₃ crystals cut at an angle of 0° (or 180°). In some non-limiting embodiments or examples, piezoelectric layer 8 formed of LiNbO3 crystals cut at an angle _of about 130° (sometimes referred to as YX-cut 130° or Y-cut 130°) is Applicants have discovered that the mode 4 resonance frequency 88 coupling efficiency M4CE can be improved or optimized. In an example, the cut angle of the piezoelectric layer 8 made of _LiNbO3 crystals is, for example, 130°±30° in the range between 100° and 160°, more preferably between 110° and 150°, for example. 130°±20° in the range, most preferably 130°±10° in the range, for example, from 120° to 140°. However, these ± values or ranges shall not be interpreted in a limiting sense.

Further, in some non-limiting embodiments or examples, the piezoelectric layer 8 (made of _LiNbO3 crystals cut at an angle of about 130° (±30°, or ±20°, or ±10°) ) and device layer 12 (when substrate 16 is omitted) or substrate 16 (when device layer 12 is omitted), or both when both device layer 12 and substrate 16 are present. Applicants have discovered that a UBAR2 formed with alternating layers of high acoustic impedance and high acoustic impedance materials can also improve or optimize the coupling efficiency M4CE of the mode 4 resonance frequency 88. In some non-limiting embodiments or examples, a UBAR 2 formed using superimposed layers of low and high acoustic impedance materials has a device layer 12 formed of diamond, SiC, W, Ir, or AlN. , and a substrate 16 formed of silicon. In some non-limiting embodiments or examples, a UBAR 2 formed using alternating layers of low and high acoustic impedance materials can include a substrate 16 formed of silicon, but not the device layer. 12 can be excluded.

Fourth example of UBAR: flexural mode (mode 4) enabled by a stack comprising at least a low acoustic impedance layer and a high acoustic impedance layer, optionally with a device layer

13, and with continued reference to FIG. 11, in some non-limiting embodiments or examples, a fourth example UBAR2 formed of alternating layers of low and high acoustic impedance materials (FIG. 13) is the piezoelectric layer 8 (made of LiNbO ₃ crystals cut at an angle of about 130° (±30°, or ±20°, or ±10°)) to the (optional) device layer 12 or substrate 16, a first low acoustic impedance layer 100, a first high acoustic impedance layer 102, a second low acoustic impedance layer 104, a second high acoustic impedance layer 106, and a third A low acoustic impedance layer 108 may also be included. In this example, the finger pitch 38 (shown in FIGS. 4A-4B) of the spaced conductive lines or fingers 20 or 28 of the top electrode 6 is 1.2 μm, the value of λ is 2.4 μm, and the piezoelectric The thickness of the layers is λ/2, the thickness of device layer 12, when present, is 4λ, and the thickness of substrate 16 is 20 μm. In this example, the cut angle of the piezoelectric layer 8 was varied between 100° and 160° for modeling.

In some non-limiting embodiments or examples, each low acoustic impedance layer 100, 104, and 108 can be formed of silicon dioxide ( _SiO2 ), and each high acoustic impedance layer 102 and 106 can be, for example, , tungsten (W), device layer 10 may be formed of diamond or SiC, and substrate 16 may be formed of silicon. In an example, device layer 12 can be optional so that third low acoustic impedance layer 108 can be in direct contact with substrate 12 and second high acoustic impedance layer 106 .

In some non-limiting embodiments or examples, to model the frequency response (frequency versus amplitude) from 100° to 160°, for example, in the manner described above for the first example of UBAR2 For each of several different cut angles of the piezoelectric layer 8 varied between degrees, for each of several different exemplary values of the thickness of the low acoustic impedance layers 100, 104, and 108: , and several different exemplary values of the thickness of the high acoustic impedance layers 102 and 106, respectively. was determined for a frequency sweep of typical electrical stimulation (eg, from 1 GHz to 6.2 GHz). In other words, the frequency response (frequency vs. amplitude) is (1) device layer 12 or no device layer 12, (2) cut angle of piezoelectric layer 8 varied between 100° and 160°, (3) low acoustic Example added to the fourth example of several UBAR2 having different combinations of impedance layers 100, 104, and 108 thickness values, and (4) high acoustic impedance layers 102 and 106 thickness values A frequency sweep of electrical stimulation (eg, from 1 GHz to 6.2 GHz) was obtained.

In some non-limiting embodiments or examples, for each cut angle of piezoelectric layer 8, the thickness of each low acoustic impedance layer 100, 104, and 108 is set to the same (initial) value, The thickness of each high acoustic impedance layer 102 and 106 was set to the same (second) value, and the frequency of the exemplary electrical stimulation applied to the fourth example of UBAR2 was, for example, 1 GHz to 6.2 GHz. , and the frequency response of a fourth example of UBAR2 to the sweep was recorded. Then the value of the thickness of the low acoustic impedance layer alone (first value) or the thickness of the high acoustic impedance layer (second value) is changed and the frequency sweep is repeated to obtain the value of the fourth example of UBAR2. Frequency response was recorded. This process uses several different low and high acoustic impedance layers to characterize the frequency response of the fourth example of UBAR2 for different values of the thickness of the low and high acoustic impedance layers. Repeated for thickness values. In some non-limiting embodiments or examples, the thickness of each low acoustic impedance layer and/or each high acoustic impedance layer may be the same or different. In some non-limiting embodiments or examples, diamond, SiC, W, Ir, AlN, etc. can be used as high acoustic impedance materials. A plot, graph, or relationship of frequency versus amplitude was obtained for each frequency sweep.

A plot, graph, or relationship of frequency vs. amplitude determined for the frequency sweep of the fourth example of EQ2 and UBAR2 can be used to construct the fourth example of UBAR2 shown in FIG. The optimum coupling efficiency M4CE of the mode 4 resonance frequency 88 in the example of is, for example, for a piezoelectric layer 8 cut at an angle of 130° and for each low acoustic impedance, for example equal to (1/16)λ For the thickness of layers 100, 104, and 108, and the thickness of each high acoustic impedance layer 102 and 106, for example equal to (1/16)λ, the following values were determined.
M4CE=15.888% for values of f _p2 and f _s2 equal to 5.43 GHz and 5.08 GHz, respectively

The foregoing values of M4CE in this example are modified because values of M4CE of 3% or greater, 4% or greater, 6% or greater, 8% or greater, or 10% or greater may be satisfactory, suitable and/or desirable. shall not be construed in a limiting sense. In examples, values of M4CE of 3% or greater, 4% or greater, 6% or greater, 8% or greater, or 10% or greater are ± suitable and/or desirable values, e.g., 130° ± It can be realized by adjusting the cut angle of the piezoelectric layer 8 by 30°. In some non-limiting embodiments or examples, without limitation, a piezoelectric layer 8 such as a _LiNbO3 crystal fabricated from a desired cut angle of Z-cut or X-cut to obtain the desired specific value of M4CE may also be sufficient for

Further, the aforementioned thickness of each low acoustic impedance layer and/or each high acoustic impedance layer may be any suitable and/or desirable thickness of each low acoustic impedance layer and/or each high acoustic impedance layer. can be of thickness such as, without limitation, 1λ or less, (1/2)λ or less, (3/8)λ or less, (1/4)λ or less, or (1/8)λ or less; It shall not be construed in a limiting sense as the thickness of each low and/or high acoustic impedance layer may be different (or the same) as the thickness of any other low and/or high acoustic impedance layer. . Thus, as used herein, the thickness of the low acoustic impedance layer is the same, the thickness of the high acoustic impedance layer is the same, or the thickness of the high acoustic impedance layer(s) and the low acoustic impedance layer That the thickness of the (s) are the same shall not be construed in a limiting sense.

Fifth example of UBAR: flexural mode (mode 4) enabled by a stack comprising at least a low acoustic impedance layer and a high acoustic impedance layer, optionally with a device layer

With continued reference to FIGS. 11 and 13, in some non-limiting embodiments or examples, in a manner similar to the UBAR2 fourth example discussed above, the piezoelectric layer 8 is between 100° and 160°. To model for each of several different cut angles, the frequency response (frequency vs. amplitude) is mostly Added to the different thickness values of the low and high acoustic impedance layers of the fifth example of UBAR2, which is similar to the fourth example of UBAR2 described above (shown in FIG. 13) in that A frequency sweep of electrical stimulation (eg, from 1 GHz to 6.2 GHz) was obtained. A plot, graph, or relationship of frequency versus amplitude was obtained for each frequency sweep.

Using the frequency vs. amplitude plot, graph, or relationship determined for the fifth example of UBAR2 and EQ2, the mode 4 resonance frequency 88 of the fifth example of UBAR2 with and without device layer 12 The optimum coupling efficiency M4CE for the piezoelectric layer 8 cut at an angle of 130° and the thickness of each low acoustic impedance layer 100 and 104 equal to (1/16)λ and (1/16)λ was determined to be the same as in the fourth example of UBAR2, namely the following values, for a thickness of each high acoustic impedance layer 102 and 106 equal to
M4CE=15.888% for values of f _p2 and f _s2 equal to 5.43 GHz and 5.08 GHz, respectively

In some non-limiting embodiments or examples, the thickness of each low acoustic impedance layer and/or each high acoustic impedance layer may be the same or different. In some non-limiting embodiments or examples, diamond, SiC, W, AlN, Ir, etc. can be used as materials for each high acoustic impedance layer.

The foregoing values of M4CE in this example are modified because values of M4CE of 3% or greater, 4% or greater, 6% or greater, 8% or greater, or 10% or greater may be satisfactory, suitable and/or desirable. shall not be construed in a limiting sense. In examples, values of M4CE of 3% or greater, 4% or greater, 6% or greater, 8% or greater, or 10% or greater are ± suitable and/or desirable values, e.g., 130° ± It can be realized by adjusting the cut angle of the piezoelectric layer 8 by 30°. In some non-limiting embodiments or examples, without limitation, a piezoelectric layer 8 such as a _LiNbO3 crystal fabricated from a desired cut angle of Z-cut or X-cut to obtain the desired specific value of M4CE may also be sufficient for

Further, the aforementioned thickness of each low acoustic impedance layer and/or each high acoustic impedance layer may be any suitable and/or desirable thickness of each low acoustic impedance layer and/or each high acoustic impedance layer. can be of thickness such as, without limitation, 1λ or less, (1/2)λ or less, (3/8)λ or less, (1/4)λ or less, or (1/8)λ or less; It shall not be construed in a limiting sense as the thickness of each low and/or high acoustic impedance layer may be different (or the same) as the thickness of any other low and/or high acoustic impedance layer. . Thus, as used herein, the thicknesses of the low acoustic impedance layers are the same, the thicknesses of the high acoustic impedance layers are the same, or the thickness of the high acoustic impedance layer(s) is low acoustic impedance. The same as the thickness of the layer(s) shall not be interpreted in a limiting sense.

This result indicates that any additional benefit, if any, of one or more additional low acoustic impedance layers between the high acoustic impedance layer 106 and the device layer 12 or substrate 16, or both indicates that it may be negligible.

A sixth example of UBAR: a bending mode (mode 4) enabled by a stack comprising at least a low acoustic impedance layer and a high acoustic impedance layer, optionally with a device layer. 14, and with continued reference to FIG. 11, in some non-limiting embodiments or examples, a sixth example UBAR2 formed of alternating layers of low and high acoustic impedance materials (FIG. 14) extends from the piezoelectric layer 8 (made of LiNbO ₃ crystals cut at an angle of about 130° (±30°, or ±20°, or ±10°)) to the element layer 12. one low acoustic impedance layer 100, a first high acoustic impedance layer 102, a second low acoustic impedance layer 104, a second high acoustic impedance layer 106, a third low acoustic impedance layer 108, and a three high acoustic impedance layers 110, a fourth low acoustic impedance layer 112, a fourth high acoustic impedance layer 114, a fifth low acoustic impedance layer 116, a fifth high acoustic impedance layer 118, a Six low acoustic impedance layers 120, a sixth high acoustic impedance layer 122, a seventh low acoustic impedance layer 124, a seventh high acoustic impedance layer 126, an eighth low acoustic impedance layer 128, and a Eight high acoustic impedance layers 130 and a ninth low acoustic impedance layer 132 may be included.

In this example, the finger pitch 38 (shown in FIGS. 4A-4B) of the spaced conductive lines or fingers 20 or 28 of the top electrode 6 is 1.2 μm, the value of λ is 2.4 μm, and the piezoelectric The thickness of the layers is (0.2)λ, the thickness of each low acoustic impedance layer is (1/16)λ, and the thickness of the device layer 12 is 4λ.

In order to model the sixth example of UBAR2 for each of several different cut angles of the piezoelectric layer 8 between 100° and 160°, the frequency response was calculated as above for the fourth example of UBAR2. Frequency sweeps of exemplary electrical stimulation applied to the sixth example of UBAR2 for several different exemplary values of the thickness of the high acoustic impedance layer in the manner described in (e.g., 1 GHz to 6.2 GHz up to). In this example, for each cut angle of piezoelectric layer 8 and for each frequency sweep, each high acoustic impedance layer has the same thickness value. A plot, graph, or relationship of frequency versus amplitude was obtained for each frequency sweep.

In some non-limiting embodiments or examples, each low acoustic impedance layer can be formed of silicon dioxide ( _SiO2 ) and each high acoustic impedance layer is formed of, for example, aluminum nitride (AlN). device layer 10 can be formed of diamond or SiC, and substrate 16 can be formed of silicon.

Using the frequency response plots, graphs or relationships determined for the sixth example of UBAR2 and EQ2, the optimum coupling efficiency M4CE for mode 4 resonance frequency 88 of the sixth example of UBAR2 is 130° and for a thickness of each high acoustic impedance layer equal to (5/16)λ, the following values were determined:
M4CE=13.287% for values of f _p2 and f _s2 equal to 5.38 GHz and 5.09 GHz, respectively

In some non-limiting embodiments or examples, the thickness of each low acoustic impedance layer and/or the thickness of each high acoustic impedance layer may be the same or different. In some non-limiting embodiments or examples, diamond, SiC, W, AlN, etc. can be used as materials for each high acoustic impedance layer.

The foregoing values of M4CE in this example are modified because values of M4CE of 3% or greater, 4% or greater, 6% or greater, 8% or greater, or 10% or greater may be satisfactory, suitable and/or desirable. shall not be construed in a limiting sense. Further, the aforementioned thickness of each low acoustic impedance layer and/or each high acoustic impedance layer may be any suitable and/or desirable thickness of each low acoustic impedance layer and/or each high acoustic impedance layer. can be of thickness such as, without limitation, 1λ or less, (1/2)λ or less, (3/8)λ or less, (1/4)λ or less, or (1/8)λ or less; It shall not be construed in a limiting sense as the thickness of each low and/or high acoustic impedance layer may be different (or the same) as the thickness of any other low and/or high acoustic impedance layer. . Thus, as used herein, the thickness of the low acoustic impedance layer is the same, the thickness of the high acoustic impedance layer is the same, or the thickness of the high acoustic impedance layer(s) and the low acoustic impedance layer That the thickness of the (s) are the same shall not be construed in a limiting sense.

In examples, values of M4CE of 3% or greater, 4% or greater, 6% or greater, 8% or greater, or 10% or greater are ± suitable and/or desirable values, e.g., 130° ± It can be realized by adjusting the cut angle of the piezoelectric layer 8 by 30°. In some non-limiting embodiments or examples, without limitation, a piezoelectric layer 8 such as a _LiNbO3 crystal fabricated from a desired cut angle of Z-cut or X-cut to obtain the desired specific value of M4CE may also be sufficient for

In some non-limiting embodiments or examples, the modeling of the first through sixth examples of UBAR2 described above is performed by computer simulation, optionally on one or more physical samples. was implemented.

In some non-limiting embodiments or examples, piezoelectric layer 8 formed of _LiNbO3 cut at an angle of 130° or about 130° optimized the value of M4CE, as described above for UBAR2 was determined from the models of the first to sixth examples of . However, it was also determined that in some non-limiting embodiments or examples, piezoelectric layer ₈ formed of LiNbO3 cut at angles between 100° and 160° also produced desirable values of M4CE. On the other hand, however, the piezoelectric layer 8 made of _LiNbO3 cut at an angle between 110° and 150° produces a more desirable value of M4CE, and cut at an angle between 120° and 140°. Piezoelectric layer 8 formed of LiNbO ₃ produced an even more desirable value of M4CE. However, the piezoelectric layer 8 made of LiNbO ₃ cut at an angle of 130° produced the most desirable (highest) value of M4CE.

In any of the examples of UBARs described herein, the thickness of the piezoelectric layer, such as LiNbO ₃ , is 0.5λ or less, 0.4λ or less, 0.3λ or less, or It may be of any suitable and/or desired thickness, such as 0.2λ or less.

In any of the examples of UBARs described herein, the thickness of the piezoelectric layer, such as LiNbO ₃ , is 2λ or less, 1.6λ or less, 1.2λ or less, or 0.8λ for shear mode—mode 3, in examples. It can be of any suitable and/or desired thickness, such as:

In any of the examples of UBARs described herein, the thickness of the electrodes, e.g. , or any suitable and/or desired thickness, such as 0.022λ or greater.

In any example UBARs described herein, the thickness of the device layer, e.g., diamond, SiC, AlN, may be any suitable thickness, e.g. and/or desired thickness.

In any example UBAR described herein, the thickness of the low acoustic impedance layer is, for example, 0.05λ or greater, 0.07λ or greater, 0.09λ or greater, 0.11λ or greater, or 0.13λ or greater. and/or any suitable and/or desired thickness.

In any example UBAR described herein, the thickness of the high acoustic impedance layer is, for example, 0.05λ or greater, 0.07λ or greater, 0.09λ or greater, 0.11λ or greater, or 0.13λ or greater. and/or any suitable and/or desired thickness.

In any of the examples of UBARs described herein, the thickness of the temperature compensating layer is any thickness, such as, in examples, 2λ or less, 1.5λ or less, 1.0λ or less, 0.5λ or less, or 0.3λ or less. may be any suitable and/or desired thickness. Optionally, one or more or all external surfaces of any example UBAR described herein may be protected with an optional passivation layer. The passivation can be, for example, a layer of dielectric material such as AlN, SiN, _SiO2 .

The resonant frequency of any example UBAR described herein may be 0.1 GHz or higher, 0.5 GHz or higher, 1.0 GHz or higher, 1.5 GHz or higher, or 2.0 GHz or higher.

The coupling efficiency of any example UBARs described herein may be 3% or greater, 4% or greater, 6% or greater, 8% or greater, or 10% or greater.

Any examples of UBARs described herein include bulk acoustic waves and shallow bulk acoustic waves, which may include, but are not limited to, _S0 mode, extension mode, shear mode, A1 mode, bending mode, etc., and synthetic It can resonate in modes including and modes.

Other non-limiting embodiments or examples are described in the numbered items below.

Item 1: A bulk acoustic resonator comprises a resonator body, wherein the resonator body is a _LiNbO3 single crystal, a piezoelectric layer, an element layer, and a top conductive layer on the piezoelectric layer opposite the element layer. Including, substantially all of the surface of the element layer opposite the piezoelectric layer is for mounting the resonator body to a carrier that is not part of the resonator body.

Item 2: The bulk acoustic resonator of Item 1, wherein the _LiNbO3 single crystal can be cut at an angle of 130°±30°, ±20°, or ±10°.

Item 3: The bulk acoustic resonator of Item 1 or 2, wherein the _LiNbO3 single crystal can be cut at an angle of 0°±30°, ±20°, or ±10° vessel.

Item 4: The bulk acoustic resonator of any one of Items 1 to 3 is mode 3 or mode at a frequency of 0.1 GHz or higher, 0.5 GHz or higher, 1.0 GHz or higher, 1.5 GHz or higher, or 2.0 GHz or higher 4 resonances can be included.

Item 5: Mode 3 resonance in which the bulk acoustic resonator of any one of Items 1 to 4 has a coupling efficiency of 8% or more, 11% or more, 14% or more, 17% or more, or 20% or more, and 3% Mode 4 resonance having a coupling efficiency of 4% or greater, 6% or greater, 8% or greater, or 10% or greater.

Item 6: The bulk acoustic resonator of any one of Items 1 to 5, wherein the LiNbO ₃ single crystal is 0.5λ or less, 0.4λ or less, 0.3λ or less, or 0.2λ for Mode 4 resonance A bulk acoustic resonator, which can have a thickness of:

Item 7: The bulk acoustic resonator of any one of Items 1 to 6, wherein the LiNbO ₃ single crystal has a wavelength of 2λ or less, 1.6λ or less, 1.2λ or less, or 0.8λ or less for mode 3 resonance. A bulk acoustic resonator that can have a thickness.

Item 8: The bulk acoustic resonator of any one of Items 1 to 7 has a conductive layer having a thickness of 0.010λ or more, 0.013λ or more, 0.016λ or more, 0.019λ or more, or 0.022λ or more. can be further included between the piezoelectric layer and the element layer.

Item 9: The bulk acoustic resonator of any one of Items 1-8, wherein the device layer can have a thickness of 50 nm or greater, 100 nm or greater, 150 nm or greater, or 200 nm or greater.

Item 10: The bulk acoustic resonator of any one of Items 1 to 9 has an acoustic impedance between 10 ⁶ Pa·s/m ³ and 30×10 ⁶ Pa·s/m ³ and 0.05λ or more, 0. A layer of low acoustic impedance material having a thickness of 07λ or greater, 0.09λ or greater, 0.11λ or greater, or 0.13λ or greater can further be included between the piezoelectric layer and the element layer.

Item 11: The bulk acoustic resonator of any one of Items 1 to 10 has an acoustic impedance between 10 ⁶ Pa·s/m ³ and 630×10 ⁶ Pa·s/m ³ and 0.05λ or more, 0. A layer of high acoustic impedance material having a thickness of 07λ or greater, 0.09λ or greater, 0.11λ or greater, or 0.13λ or greater can further be included between the piezoelectric layer and the element layer.

Item 12: The bulk acoustic resonator of any one of Items 1 to 11 has a thickness of 2λ or less, 1.5λ or less, 1.0λ or less, 0.5λ or less, or 0.3λ or less and contains Si and oxygen. between the piezoelectric layer and the device layer.

Item 13: The bulk acoustic resonator of any one of Items 1-12 can further include a passivation layer.

Item 14: The bulk acoustic resonator of any one of items 1-13, wherein the top conductive layer can include at least one pair of spaced-apart conductive fingers. At least one pair of spaced-apart conductive fingers can have a finger pitch of 70 μm or less, 20 μm or less, 10 μm or less, 6 μm or less, or 4 μm or less.

Item 15: The bulk acoustic resonator of any one of items 1-14 can further include a plurality of alternating temperature-compensating layers and high acoustic impedance layers between the piezoelectric layer and the element layer.

Item 16: The bulk acoustic resonator according to any one of Items 1 to 15, wherein the element layer comprises diamond; W; SiC; Ir, AlN, Al; Pt; transition elements of groups 1B, 2B, 3B, 4B, 5B, 6B, 7B or 8B of the periodic table; ceramics; glasses; and polymers. , bulk acoustic resonator.

Although the present invention has been described in detail for purposes of illustration based on what are presently considered to be the most practical preferred and non-limiting embodiments, examples, or aspects, such details are The present invention is not limited to the preferred and non-limiting embodiments, examples, or aspects disclosed, but rather is intended to encompass modifications and equivalent arrangements within the spirit and scope of the appended claims. It should be understood that For example, to the extent possible, the present invention applies one or more features of any preferred and non-limiting embodiment, example, aspect, or appended claim to any other preferred and non-limiting It is contemplated that any one or more of the embodiments, examples, aspects, or features of the appended claims may be combined.

Claims (17)

A bulk acoustic resonator,
a resonator body, the resonator body comprising:
A piezoelectric layer that is a LiNbO ₃ single crystal, the LiNbO ₃ single crystal being Y-cut at an angle rotated about its X-axis and having a thickness, the angle and the a piezoelectric layer, the thickness of which provides mode 3 or mode 4 resonance at a given coupling efficiency;
an element layer located below the piezoelectric layer , the element layer being formed of diamond or SiC and having a thickness of 50 nm or more;
a top conductive layer overlying the piezoelectric layer opposite the device layer, the top conductive layer including at least one pair of spaced-apart conductive fingers; A bulk acoustic resonator, wherein all surfaces of the element layer opposite the piezoelectric layer are for mounting the resonator body to a carrier that is not part of the resonator body. 2. The bulk acoustic resonator of claim 1, wherein said _LiNbO3 single crystal is cut at said angle of 130[deg.]±30[deg.]. 2. The bulk acoustic resonator of claim 1, wherein said _LiNbO3 single crystal is cut at said angle of 130[deg.]±20[deg.]. 2. The bulk acoustic resonator of claim 1, wherein said _LiNbO3 single crystal is cut at said angle of 130[deg.]±10[deg.]. 2. The bulk acoustic resonator of claim 1, wherein said _LiNbO3 single crystal is cut at said angle of 0[deg.]±30[deg.]. 2. The bulk acoustic resonator of claim 1, wherein said _LiNbO3 single crystal is cut at said angle of 0[deg.]±20[deg.]. 2. The bulk acoustic resonator of claim 1, wherein said _LiNbO3 single crystal is cut at said angle of 0[deg.]±10[deg.]. 8. The bulk acoustic resonator of claim 7, comprising said mode 3 or said mode 4 resonance at frequencies of 0.1 GHz or higher. the Mode 3 resonance having the predetermined coupling efficiency of 8% or more;
3. The bulk acoustic resonator of claim 1, comprising at least one of said Mode 4 resonance having said predetermined coupling efficiency of 3% or greater. In the Mode 4 resonance, the LiNbO ₃ single crystal has a thickness of 0.5λ or less, and the value of λ is based on the dimensions of the pattern or features defined by the top conductive layer, or the LiNbO 10. The bulk acoustic resonator of claim 9, based on said thickness of ₃ single crystals. In the Mode 3 resonance, the LiNbO ₃ single crystal has a thickness of 2λ or less, and the value of λ is based on the dimensions of the pattern or features defined by the top conductive layer, or the LiNbO ₃ single crystal 10. The bulk acoustic resonator of claim 9, based on said thickness of a crystal. further comprising a bottom conductive layer having a thickness greater than or equal to 0.010λ at a location between the piezoelectric layer and the device layer, wherein the value of λ is based on a dimension of a pattern or feature defined by the top conductive layer; , or based on the thickness of the _LiNbO3 single crystal. A layer of a low acoustic impedance material having an acoustic impedance of between 10 ⁶ Pa·s/m ³ and 30×10 ⁶ Pa·s/m ³ and a thickness of 0.05λ or more is provided between the piezoelectric layer and the element layer. 2. The bulk acoustic according to claim 1, further comprising at a position between and wherein the value of λ is based on a dimension of a pattern or feature defined by said top conductive layer or based on said thickness of said _LiNbO3 single crystal. resonator. A layer of a high acoustic impedance material having an acoustic impedance between 10 ⁶ Pa·s/m ³ and 630×10 ⁶ Pa·s/m ³ and a thickness of 0.05λ or more is provided between the piezoelectric layer and the element layer. 2. The bulk acoustic according to claim 1, further comprising at a position between and wherein the value of λ is based on a dimension of a pattern or feature defined by said top conductive layer or based on said thickness of said _LiNbO3 single crystal. resonator. further comprising a temperature compensating layer having a thickness of 2λ or less and comprising Si and oxygen at a location between said piezoelectric layer and said device layer, wherein the value of λ is equal to or less than the pattern or feature defined by said top conductive layer. The bulk acoustic resonator of claim 1, based on dimensions or based on the thickness of the _LiNbO3 single crystal. 3. The bulk acoustic resonator of Claim 1, further comprising a passivation layer. 3. The bulk acoustic resonator of claim 1, further comprising a plurality of alternating temperature compensating layers and high acoustic impedance layers at locations between the piezoelectric layer and the device layer.

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